Simple way to make a Call from lock screen

Hi,
I am looking for some way so that my kids can make a call to one of the parents even it the phone is locked. I know about adding an ICE emergency contact but that is a too complicated way to make call.

Ideally what I am looking for is a fixed notification (with a picture) so that when touched it makes a call. (I can alternatively be a widget placed on lockscreen. However Notification would be better since the steps to make a call would be same whether the phone is locked or not.)